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prefect.plugins

Utilities for loading plugins that extend Prefect's functionality.

Plugins are detected by entry point definitions in package setup files.

Currently supported entrypoints
  • prefect.collections: Identifies this package as a Prefect collection that should be imported when Prefect is imported.

load_prefect_collections()

Load all Prefect collections that define an entrypoint in the group prefect.collections.

Source code in src/prefect/plugins.py
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def load_prefect_collections() -> Dict[str, Union[ModuleType, Exception]]:
    """
    Load all Prefect collections that define an entrypoint in the group
    `prefect.collections`.
    """
    global COLLECTIONS

    if COLLECTIONS is not None:
        return COLLECTIONS

    collection_entrypoints: EntryPoints = entry_points(group="prefect.collections")
    collections = safe_load_entrypoints(collection_entrypoints)

    # TODO: Consider the utility of this once we've established this pattern.
    #       We cannot use a logger here because logging is not yet initialized.
    #       It would be nice if logging was initialized so we could log failures
    #       at least.
    for name, result in collections.items():
        if isinstance(result, Exception):
            print(
                # TODO: Use exc_info if we have a logger
                f"Warning!  Failed to load collection {name!r}:"
                f" {type(result).__name__}: {result}"
            )
        else:
            if prefect.settings.PREFECT_DEBUG_MODE:
                print(f"Loaded collection {name!r}.")

    COLLECTIONS = collections
    return collections

safe_load_entrypoints(entrypoints)

Load entry points for a group capturing any exceptions that occur.

Source code in src/prefect/plugins.py
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def safe_load_entrypoints(entrypoints: EntryPoints) -> Dict[str, Union[Exception, Any]]:
    """
    Load entry points for a group capturing any exceptions that occur.
    """
    # TODO: `load()` claims to return module types but could return arbitrary types
    #       too. We can cast the return type if we want to be more correct. We may
    #       also want to validate the type for the group for entrypoints that have
    #       a specific type we expect.

    results = {}

    for entrypoint in entrypoints:
        result = None
        try:
            result = entrypoint.load()
        except Exception as exc:
            result = exc

        results[entrypoint.name or entrypoint.value] = result

    return results